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Wang Y.,China University of Geosciences | Wang Y.,U.S. Geological Survey | Mooney W.D.,U.S. Geological Survey | Yuan X.,China Geological Survey | Okaya N.,U.S. Geological Survey
Tectonophysics | Year: 2013

We present a new crustal cross section of the northeastern Tibetan plateau based on active-source seismic data recorded along a 1600-km-long profile crossing the southern Tarim basin, the western flank of the South-Qilian Shan, the northeastern margin of Qaidam basin, East-Kunlun Shan, Songpan-Ganzi terrane, and Sichuan basin. The crustal P- and S-wave velocity structure and Poisson's ratio outline the seismic characteristics of the crust and provide constraints on the crustal composition. The derived crustal cross section shows several significant features. (1) The crustal thickness varies considerably along this profile, from 48. km to 70. km. (2) North of the Kunlun fault variations in total crustal thickness are mainly caused by variations in lower crustal thickness, whereas south of the Kunlun fault they are caused by thickness variations throughout the crust. (3) North of the Kunlun fault we detect a mid-crustal low-velocity zone that is not apparent south of the fault. (4) The Kunlun fault seems to act as a compositional boundary for the lower crust, with a Poisson's ratio of 0.29 north of the fault (Kunlun-Qaidam terrane) and 0.26 south of the fault (Songpan-Ganzi terrane). Measured Poisson's ratio and P-wave velocity values suggest that the lower crust throughout the Tibetan plateau (South-Qilian Shan, margins of the Qaidam Basin, East-Kunlun Shan, Songpan-Ganzi terrane) is of intermediate composition. Thus the NE Tibetan plateau along our profile is missing a mafic lower crustal layer. © 2012 . Source


Guo H.,China University of Geosciences | Guo H.,Water Resources University | Wen D.,China Geological Survey | Liu Z.,Water Resources University | And 4 more authors.
Applied Geochemistry | Year: 2014

China is a typical high-As region, where 20 provinces have high As groundwaters among 34 provinces. These groundwaters usually occur in both arid-semiarid inland basins and river deltas. In the inland basins, mainly distributed in the northwest of China, shallow groundwaters usually have high As concentrations in alluvial lacustrine or lacustrine sediment aquifers, while high As groundwater mainly occurs in fluvial-marine sedimentary aquifers in the river deltas, which have been affected by transgression. In both the inland basins and the river deltas, high As groundwaters, mainly occurring in reducing conditions, are characterized by high Fe and Mn concentrations, high pH and HCO3- concentration, and relatively low NO3- and SO42- concentrations. Although As contents are well correlated to Fe/Mn contents in the aquifer sediments, groundwater As concentrations are generally independent of sediment As contents. Redox processes, microbe-related reduction, and desorption processes are the major geochemical processes for As enrichment in groundwaters. In reducing conditions, both reductive dissolution of Fe oxides and reductive desorption of As are believed to result in As mobilization, which would be catalyzed by indigenous microbes. Although decomposition of the low-molecular weight organic matter during microbe metabolization would also release the colloid-bound As into groundwater, the cycling of colloidal As still needs to be further investigated during redox processes. Besides, high pH and high HCO3- lead to As desorption from adsorption sites in the aquifer systems. However, the contribution of competitive desorption to high As concentrations is still unknown and remains to be discovered, relative to reductive dissolution of Fe oxides, especially in the inland basins. © 2014 Elsevier Ltd. Source


Jiao J.J.,University of Hong Kong | Wang Y.,University of Hong Kong | Cherry J.A.,University of Guelph | Wang X.,Water Resources University | And 3 more authors.
Environmental Science and Technology | Year: 2010

High-nitrogen loadings of rivers and aquifers systems are a major concern because of potential effects on human health and water quality impacts such as eutrophication of lakes and coastal zones. This nitrogen enrichment is commonly attributed to anthropogenic sources such as sewage and agricultural and industrial wastes. The aims of this study were to delineate spatial distribution of groundwater ammonium in the coastal aquifer system in Pearl River Delta (PRD), China and to identify the origin of the abnormally high ammonium. A total of 40 boreholes were drilled to collect core samples of the aquitard and groundwater samples in the basal aquifer. The core samples were used for extraction of pore water for centrifugation and bulk chemical analyses in laboratory. Unlike previous studies which focused mainly on the aquifer, this study treated the aquifer-aquitard system as a hydrogeochemical continuum. The results show that the aquifer-aquitard system contains an exceptionally large total ammonium mass. Ammonium occurred at concentrations up to 390 mg/L in the basal sand Pleistocene aquifer 20-50 m deep, the largest concentration reported for groundwater globally. This ammonium was natural, areally extensive (1600 km2) and originated in the overlying Holocene-Pleistocene aquitard and entered the aquifer by groundwater transport and diffusion. Total ammonium in the aquifer (190 × 106 kg) was exceeded by total ammonium in the aquitard (8600 × 106 kg) by a factor of 45. Much organic nitrogen remained in the aquitard available for conversion to ammonium. This natural ammonium in the aquifer was slowly transported into the PRD river channels and the estuary of the South China Sea. The rate of this contribution will likely be greatly increased by sand dredging in the river channels and estuary. Although the ammonium in PRD groundwater occurred in the largest concentrations and mass reported globally, the literature shows no reports of other delta aquitards having been examined for ammonium occurrence and therefore abundant ammonium formed in aquitards rich in organic matter may not be uncommon and this "geologic" source of ammonium may present a large and hitherto unappreciated source of nitrogen discharging to surface waters. © 2010 American Chemical Society. Source


Yin Y.,China Geological Survey | Xing A.,Shanghai JiaoTong University
Bulletin of Engineering Geology and the Environment | Year: 2012

On the April 9 of 2000, a gigantic rapid rock slide-debris avalanche occurred in Bomi, Tibet. Some 280-300 × 10 6 m 3 of material travelled 10 km within 10 min and dammed the Yigong River, forming a 2.9 × 10 9 m 3 barrier lake. Wind tunnel testing was undertaken to determine the aerodynamic parameters involved, from the initial rock slide-fall to its point of impact. The paper reports the numerical analyses undertaken and discusses the significance of the air-cushion effect. It is concluded that Yigong rapid rock slide-debris avalanche "flew" in the air for about 12.9 s from its detachment from the source to its collision with the floor of the Zamunong gully at 3,317 m asl. The velocity of the avalanche mass at the point of detachment was some 81.8 m/s and the collision velocity approximately 117 m/s. © 2011 Springer-Verlag. Source


Liu D.-W.,China Geological Survey
Geology in China | Year: 2015

Based on an analysis of the substantive connotation of the "Belt and Road", this paper systemically discusses the issues about how to construct the "Belt and Road" in the field of geological survey, including principles, cooperation areas, cooperation mechanisms, working foundation, recent deployment and planning as well as bottleneck problems. Following the "common development" main line of building "Belt and Road" and adhering to the philosophy of "peace and cooperation, openness and inclusiveness, mutual learning and mutual benefit", the cooperation working contents include earth sciences joint research, fundamental geological survey, hydrogeological survey, engineering geological investigation, environmental geological survey, marine geological survey, geo-hazard investigation, evaluation, monitoring and mitigation, and geo-information sharing and so on. Through the establishment of the bilateral, multilateral, subregional, regional cooperation mechanisms and cooperation platform cooperation, technical, personnel and cultural exchanges and cooperation, geological survey will support and serve "Belt and Road" sustainable development. This paper proposes two important issues, i.e., the international cooperation mechanism construction and the international cooperation personnel training, which should be resolved during the building of "Belt and Road" of geological survey. In addition, some related suggestions are put forward. Source

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